package java_algorithm;

//给出两个 非空 的链表用来表示两个非负的整数。其中，它们各自的位数是按照 逆序 的方式存储的，并且它们的每个节点只能存储 一位 数字。
//如果，我们将这两个数相加起来，则会返回一个新的链表来表示它们的和。
//您可以假设除了数字 0 之外，这两个数都不会以 0 开头。
//示例：
//
//输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)
//输出：7 -> 0 -> 8
//原因：342 + 465 = 807

public class demo002 {
    public static void main(String[] arge){
        ListNode l1 = new ListNode(2);
        l1.next = new ListNode(4);
        l1.next.next = new ListNode(3);
        ListNode l2 = new ListNode(5);
        l2.next = new ListNode(6);
        l2.next.next = new ListNode(4);
        ListNode ret = new demo002().addTwoNumbers(l1,l2);
        System.out.println(ret);
    }

    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode ret = new ListNode(0);
        ListNode node = ret.next;
        node = new ListNode(0);
        int rest = 0;
        for (;l1 != null && l2 != null ;){
            int amount = (null == l1?0:l1.val) + (null == l2?0:l2.val) + rest;
            rest = amount / 10;
            amount = amount % 10;

            if(null != l1) l1 = l1.next;
            if(null != l2) l2 = l2.next;

            node.val = amount;
            if(null == ret) ret = node;
            if(l1 != null && l2 != null) node.next = new ListNode(0);
            node = node.next;
        }
        return ret.next;
    }
//    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
//        ListNode dummyHead = new ListNode(0);
//        ListNode p = l1, q = l2, curr = dummyHead;
//        int carry = 0;
//        while (p != null || q != null) {
//            int x = (p != null) ? p.val : 0;
//            int y = (q != null) ? q.val : 0;
//            int sum = carry + x + y;
//            carry = sum / 10;
//            curr.next = new ListNode(sum % 10);
//            curr = curr.next;
//            if (p != null) p = p.next;
//            if (q != null) q = q.next;
//        }
//        if (carry > 0) {
//            curr.next = new ListNode(carry);
//        }
//        return dummyHead.next;
//    }
}

/**
 * 链表节点
 */
class ListNode {
    int val = 0;
    ListNode next;

    ListNode(int x) {
        val = x;
    }

    @Override
    public String toString() {
        StringBuffer strBuf = new StringBuffer();
        for (ListNode theNext = this; theNext != null; theNext = theNext.next){
            if(strBuf.length() != 0) strBuf.append(" -> ");
            strBuf.append(theNext.val);
        }
        return strBuf.toString();
    }
}
